The Save / Data menu function creates a backup version of the contents of the serverdb.
For backups in WARM mode, it must be taken into account that the database is saved with the state when the backup operation was started. Modifications to the contents of the database made during the backup operation are not saved.
Save / Data can also be executed in COLD mode. To be able to create a consistent database with the generated backup version without having to restore more log devspaces during a subsequent Restore, the database must be in a consistent state when saving. A database is in a consistent state, when it was switched into COLD mode using the Operating / Shutdown ~/ Cold Ok (not Quick) menu function.
It is necessary to perform a complete backup in adequate time intervals (e.g., at least weekly).
To ensure maximum data throughput, Save / Data can be used to simultaneously back up the serverdb to several media. The maximum number of media to which simultaneous writing is possible can be set as configuration parameter (see MAXBACKUPDEVS in Section Installing a New Serverdb under "configuration parameters" and Section Configuration / Alter Parameters / Kernel). If a parallel backup to several media is to be performed, a group of media must be defined as parallel media in the Media Manager.
CONTROL displays the following screen that must be confirmed:
The number of tapes required determines the behavior of CONTROL during the save or restore operation. CONTROL saves or restores simultaneously until the number of required media has been reached. All
the media required beyond the specified number are sequentially written. Thus it can be controlled that either as few media are used as possible or rather a maximum save or restore speed is obtained
(then a large number must be specified). The number of required media can be changed after pressing the 
key.
The following schemes shall illustrate the reaction of CONTROL. In the three example cases, six tapes are needed for the data save and four tape devices are used in parallel. Writing a tape up to its end takes an hour.
a) CONTROL takes the last number of media used for this save as the number of tapes (six in the example). After about an hour, the four tape devices are ready and request the next tape, one after the other. In this case, only two of the four free tape devices request a tape; the other two tape devices are ignored by CONTROL.
b) With eight tapes provided, the four tape devices that have become free give notice one after the other expecting another tape. The rest of the save can be done faster, because four tapes, instead of two, are simultaneously written.
c) If less tapes are specified than needed (e.g. four), the last tape device that has become free gives notice requesting all the tapes required one after the other. This variant of save takes the most time, but all tapes, except the last one, are written up to their ends.
